Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the write/overwrite profile is covered. The description's one real addition is 'Draft until publish', which tells the agent the change is staged and does not go live immediately — valuable, but the description says nothing about whether the asset must be uploaded first or what remove=true destroys.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short, front-loaded sentences with no filler; the core action leads and the staging caveat follows. The terseness is arguably under-specification rather than wordiness, which is penalized in other dimensions.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a destructive five-parameter mutation with no output schema and only 40% schema coverage, the definition is thin: it never explains the enum variant, the remove flag, or the required site slug. An agent would have to infer significant behavior before calling it safely.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is only 40% across five parameters, so the description must carry meaning for the undocumented ones and largely does not. Only 'square image asset' loosely maps to assetKey; 'remove', 'variant' (enum default/dark), and the required 'site' slug get no descriptive treatment.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource pair ('Set the favicon') and adds an input constraint ('from a square image asset'), so the agent knows exactly what the call changes. It does not name or contrast with any sibling, so an agent cannot tell from the description alone why this differs from, say, update_site or publish_site.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'From a square image asset' implies a precondition (you must already have a square image asset to point at), and 'Draft until publish' implies the change is staged. There is no explicit when-not guidance and no mention of when to use 'remove' versus supplying a new 'assetKey'.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.